test that the () and {} forms of Vc::vector work as for std::vector
move simd_cast into separate headers and make it work for more cases
start using a new macro for the AVX namespace name
implement casts between (un)signed int/short
make operator[] in Vc::array always_inline and prefer forward(arg__) instead of declval
move the common interface of load ctors/functions into separate file and ensure the Flags type is a LoadStoreFlag
move the common interface of store functions into a separate file and ensure the Flags type is a LoadStoreFlag
fix include guard to use the right directory name
break out is_gather_signature trait